I personally don't like to drink alcohol and currently because of my medication I cannot drink it anyway.
This year at Uni I've been lucky enough to be housed with people that arn't too fond of drinking either. Some like to drink but they don't do excessively which is fine and they don't pressure anyone else to drink either. We have two of those "it's no fun till your black out drunk" kind of girls who complain we don't include them in flat activities though we have asked if they'd like to come out for a meal (Which was my birthday and I personally invited them myself) , watch films, play games and invited them to Hull fair last month. Otherwise no you do not need to drink alcohol to have a good time, nor do you need to take drugs.
There's always going out to the cinema, playing board games (We have monopoly nights once a week), ice skating , laser quest, playing video games that include lots of players like Smash Bros and guitar hero, paint ball, baking, and watching films in the flat . It really doesn't need that much of imagination to have a good time.